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D. Rodriguez (Florida Institute of Technology), R. M. Rich, M. Morris, D. Reitzel (UCLA), A. Gil de Paz (Carnegie Obs.)
We observe M32 in a wide range of wavelengths from the far ultraviolet to the infrared. Images are taken from GALEX, Spitzer, HST, and Keck. Color gradients in the different passbands are measured using isophotes derived from the fitting of optical surface photometry. We also take care to subtract spatially variable backgrounds that are evident in the far UV and at 8 microns. Most of the color gradients are fairly constant, with colors becoming only marginally redder with distance from the center of M32. We can infer that the stellar populations must be roughly the same at all radii from the galaxy. A redder color is observed within 2 arcseconds (corresponding to about 7 parsecs) of the nucleus. STIS FUV/NUV division images show a dark area that may be due to dust in the central region. This dust could be responsible for the observed reddening and might come from the envelopes of AGB stars as observed in the IRAC 8 micron image. Additionally, point sources are found in IRAC 8 micron images. The fuel consumption theorem is applied to determine the lifetime of those stars and a value of about 27,000 or 44,000 years (depending on the method used) is obtained. This value is close to the expected lifetime of the AGB phase. Our images also show star formation (see in the GALEX FUV and NUV bands) and PAH emission (Spitzer 8 micron band) in the M31 disk.
Funding is acknowledged from Spitzer program P3400. DR acknowledges support from the NSF REU program. RMR acknowledges additional funding from NASA, through participation in the Galaxy Evolution Explorer science team.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.